5.3 Sedimentary Rocks


Vocabulary


Sediment: small solid pieces of material that come from rocks or living things
Erosion: occurs when running water or wind loosen and carry away the fragments of rock
Deposition: process by which sediment settles out of the water or wind carrying it
Compaction: process that presses sediments together
Cementation: process in which dissolved minerals crystallize and glue particles of sediment together
Clastic Rocks: sedimentary rock that forms when rock fragments squeeze together
Organic Rocks: forms where the remains of plants and animals are deposited in thick layers
Chemical Rocks: forms when minerals that are dissolved in a solution crystallize

Outline


  • From sediment to rock
    • erosion
      • forces break up and wear away rocks on earth's surface
        • forces include
          • heat
          • cold
          • rain
          • waves
          • grinding ice
    • deposition
      • after sediments are deposited process of compaction and cementation change sediments into sedimentary rock
      • sediments include
        • shells
        • bones
        • leaves
        • stems
        • other remains of living things
    • compaction
      • after millions of years sediments build up
      • layers are heavy and press down on the layers beneath
      • after, compaction happens
      • then, the weight gets really heavy so it squeezes tightly
      • becomes sedimentary rock
      • layers are visible
    • cementation
      • during compaction, minerals in rock dissolve in water
        • goes into spaces between particles of minerals
      • millions of years for compaction and cementation to change loose sediments into solid sedimentary rock
  • Types of sedimentary rock
    • clastic rocks
    • organic rocks
    • chemical rocks
  • Clastic rocks
    • shale
      • common
      • forms from tiny particles of clay
      • feels smooth
      • splits easily into flat pieces
    • sandstone
      • forms from sand from
        • beaches
        • ocean floor
        • riverbeds
        • in sand dunes
      • easily absorbs water through holes
    • conglomerate and breccia
  • Organic rocks
    • coal
      • forms from the remains of swamp plants buried in water
    • limestone
      • made from shells or skeletons (that have calcite) of
        • coral
        • clams
        • oysters
        • snails
          • when they die, shells pile up as sediment on ocean floor
          • after millions of years pressure begins, then dissolved material comes out of solution
            • calcite cements shell particles and forms limestone
      • chalk is most common
  • Chemical rocks
    • forms when minerals dissolve in solution and crystallizes
    • forms from mineral deposits left when seas or lakes evaporate
    • gypsum
  • Uses of sedimentary rocks
    • decorates things
    • covers outside walls of buildings

Diagram






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